Fume hoods are laboratory accessories that prevent workers from being exposed to hazardous and dangerous fumes while working on them. In the early days, they were made of wood. Today, they are made of mild steel coated with epoxy. The change in construction and style has been introduced to make them safer for laboratory workers. There are two main types of hoods, the ducted and the re-circulating ones. In both units, air is drawn in from the front of the cabinet by use of a fan, and either expelled outside the building or filtered then fed back to the workplace.
Re-circulating fume hoods
This type of hood is used for educational purposes, or in buildings that do not permit external ductwork to be fitted. In addition, this hood has a fan fixed on top, or below the worktop. It sucks air through the opening in front of the hood and later through a filter; the air passes through the fan and finally is fed back to the workplace. Re-circulating fume hoods or standard size fume hoods are of different sizes. Their sizes range from 4′ to 8′. However, some companies can build hoods to fit your laboratory specifications.
The main disadvantage of this type of hood is that workers working close to these fume hoods are more likely to be exposed to harmful chemicals than when using ducted fume hoods. The other health concern is that workers working near this hood are exposed to noise because the extract fan is near the workplace.
Ducted fume hoods
These types of hoods are for industrial purposes. They remove air from the workspace and disperse it into the atmosphere. In order to improve indoor air quality, some labs use single-pass air handling systems, where heated or cooled air is used once and then discharged. On the other hand, labs that want to minimize energy costs usually use return air systems which provide adequate ventilation rates and appropriate working conditions.
The main advantage of this type of hood is that it enables workers to work in a safe environment by eradicating fumes from the workplace and by reducing noise pollution due to the distance of the fan from the workplace. The main disadvantage is that it needs additional ductwork and therefore is more expensive. It also pollutes the atmosphere because it does not treat the fumes that disperse into the atmosphere.
Safety tips to consider when dealing with or using fume hoods
- If possible, work with less hazardous materials to reduce the chances of exposure to harmful fumes.
- Make sure that the exhaust fans of hoods are functioning properly to ensure that your workplace is free from air pollution.
- Do not place your head inside the hood to avoid exposure to harmful fumes.
- In order to minimize the cost of energy used by hoods, always close the hood sash.
- Nothing should be stored or disposed in the hood to prevent the blockage of airflow.
To ensure that your fume hoods manage the hazards posed by chemical vapors or airborne substances, it is important to let the professionals of the companies that build the hoods, install them if you are not familiar with them.